1. Field of the Invention
The present invention relates to tire pressure indicating systems in general, and more particularly to such systems offering digital and analog tire pressure indicators and easy access tire fill valves for single and dual wheel tire assemblies.
2. Description of the Related Art
Fuel and tires represent the greatest operating cost for a single tractor/trailer or an entire fleet. If a truck tire that normally operates at 100 psi is 25-30% under inflated, which causes excessive tread wear due to heat and friction and reduces fuel efficiency due to resistance and drag. At today""s average cost of $200-$300 per tire, under inflation could account for as much as $75 per tire in tire costs alone. Under inflation also negatively impacts the longevity of tire casings. Proper air maintenance assures that tires can be recapped up to five times.
Prior art methods and devices for maintaining proper tire pressure include pressure gauges that are carried by the driver and which are used to periodically check the tire pressure and to fill the tires to proper levels. It is also known to use tire gauges or indicators, which are permanently mounted to the tire valve stem to provide a readout of the tire pressure when viewed by the truck operator.
Truck drivers most commonly use the manual pressure gauges to check tire inflation pressure usually after first tapping the tire with their foot or tool and finding that it was low. Such a check detects a low tire only after a significant loss of tire pressure. On a slow leak, the tire has been operating at low pressure for some time and some tire degradation has already occurred. Also, over pressure is not detectable by such tapping of the tire.
Permanently mounted tire gauges and indicators on the tire valve stem adjacent the rim are small in size and require the operator to bend down to the tire level before the operator can see the gauge pressure reading. Some gauges mounted away from the rim tire valve are actually covered with a cover and required an effort on the part of the operator to remove the cover before checking the gauges. No known permanently mounted tire pressure maintenance systems offer an easily seen gauge which can be easily viewed by the truck operator as the operator walks by the wheels of a stationary vehicle to see if the inflation pressure is in the proper range (neither under inflated nor over inflated).
One known specific example is the permanently mounted tire inflation indicator is found in U.S. Pat. No. 3,958,526. An under inflation type warning system is disclosed where a collapsible bladder mounted axially on the wheel is connected to a tire and is inflated whenever the tire pressure falls below a predetermined level. However, there is no warning provided by this system for a slowly leaking tire or for over inflation. There is no easily seen gauge which will show the pressure in the tire at all times and will guide the operator in inflating the tire to the proper level. The system uses the conventional tire fill valves.
Another example may be found in U.S. Pat. No. 4,387,931. Here a pressurized container regulated to the desired tire pressure is continuously connected to all of the tires to thus maintain them all at the proper pressure level. However, this system provides no actual gauge readings of tire pressure and a failure of the pressure regulator or the container could result in an undetected over pressurized or under pressurized condition in all of the tires. There are no conventional tire fill valves used.
A dual-tire, wheel assembly tire pressure indicating system is disclosed in U.S. Pat. No. 4,953,395. The gauge or gauges are located in the center hub of the wheel and hence are covered with a removable cover requiring the operator to bend down to wheel level to uncover and view the gauges. Further, there is no indication that the gauges offer any area markings thereon to indicate proper or improper inflation along with an analog pressure readout thereon to aid tire inflation to the optimal tire pressure of 100 psi., nor is there any logo identifying which gauge is for the front and which for the back tire of the dual wheel assembly.
Another conventional dual-tire, wheel assembly tire pressure indicating system is disclosed in U.S. Pat. No. 5,770,797. The tire pressure indicating system includes a pair of analog/digital readout pressure gauges mounted on a full wheel streamlined hubcap. The hubcap is mounted to the outside wheel of the dual wheel assembly by a U-shaped bracket connected to the wheel through the wheel bolts with the hubcap connected thereto by quarter turn fastener assemblies.
However, the inventor of the present invention has recognized that a problem associated with such prior devices is that, in the event the device becomes detached from the valve stem while the automobile is in motion, the device may become a high velocity projectile and thus present a safety hazard.
Another problem recognized by the inventor of such prior devices is that, because of the eccentricity of the load that they add to the tire, the automobile""s tire may become unbalanced, thus presenting a safety problem and causing an uneven and unsafe ride for the automobile""s passengers.
Another problem of such prior devices recognized by the inventor is that they require the use of a mounting device for the tire pressure gauges, such as a hubcap assembly mountable to the front wheel of a deep dish dual wheel assembly through a bracket assembly connected by wheel bolts or nuts to oppositely located studs of the outside wheel of the dual wheel assembly. Such a tire pressure indication system is disclosed in U.S. Pat. No. 5,770,797 to Lapohn, herein incorporated by reference. This unnecessary practice of providing a tire pressure indication system mounted to a hubcap assembly increases the cost and weight associated with the tire pressure indication system.
To solve these and other problems, one aspect of this invention is to provide a tire pressure indication system for a tire wheel having an easily visible tire pressure gauge and a tire inflation valve stem mounted proximately thereto.
Another aspect of this invention is to provide a device in which the tire pressure sensing device is attachable to the valve stem of common automobile tires.
Yet another aspect of this invention is to provide a device in which the tire pressure sensing and indicating device may remain attached to the tire""s valve stem while the tire is in motion.
Still another aspect of this invention is to provide a device that introduces minimal eccentric loads to the tire.
Yet another aspect of this invention is to provide a device in which the pressure indicating device is either a dial gauge or a digital gauge.
Still yet another aspect of this invention is to provide a device in which the gauge is protected from damage by debris.
Yet another aspect of this invention is to provide a device which can be attached to existing automobile wheels and tires without modification of the wheels or tires.
Another aspect of this invention is to provide a device that can be securely fastened to the rim of a tire and in a manner that prevents theft of the device.
Another aspect of this invention is to provide a tire pressure indicating system for a dual-wheel tire assembly having a pair of large off-center spaced digital tire pressure gauges whose proper pressure range is easily seen by a truck operator walking by the wheel assembly.
Yet another aspect of this invention is to provide a tire pressure maintenance system for a dual-wheel tire assembly having a pair of off-center spaced tire pressure gauges with associated tire fill valve stems located proximate to each gauge to allow the monitored inflation of the tire monitored by the associated gauge.
According to the invention, a tire pressure indication system comprises a bracket structure mounted to an inside surface of a wheel assembly by use of an adhesive tape, at least one air pressure gauge mounted to the bracket structure; and a pneumatic conduit being in communication with the at least air pressure gauge and a valve stem of a pneumatic tire, wherein the at least one air pressure gauge provides an indication of air pressure of the pneumatic tire to an operator.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.